ignorenonframetext as an option to Beamer, causes it to ignore all the text that is not inside a frame. It is useful when you want to add content for the article version of the presentation (or simply script lines for yourself) that would not show in the regular presentation. LyX puts the title elements outside any frame. Therefore, if you use
ignorenonframetext you end up missing the title frame. The solution is to manually wrap the title block (the title, author, institute, etc.) in a frame and append to it
\maketitle. This will cause the title frame to be rendered correctly.
LyX: Missing title when passing `ignorenonframetext` to Beamer